1. Field of the Invention
The present invention is directed toward systems and methods for controlling cooling fluid temperature within a vehicular engine compartment.
2. Description of the Related Art
A vehicle engine compartment, such as one containing a fuel cell, often contains more than one device using a single cooling fluid supply. Cooling fluid supply lines may be routed through a heat exchanger to cool the fluid, then may be used to cool other components located downstream, such as the fuel cell or a condensing heat exchanger. However, the set point temperature requirement of the fuel cell may be significantly different than the set point temperature requirement of the condensing heat exchanger or other devices. The set point temperature is the temperature specified by the manufacturer that will permit the given device to operate optimally and efficiently.
A common solution for cooling multiple components with only one heat exchanger has been to accept the fact that one or both of the downstream components will receive cooled system fluid that is not on par with the component's set point temperature. For example, if a fuel cell has a set point temperature requirement of 200° F., but the condensing heat exchanger has a set point temperature of only 100° F., then all of the system fluid is commonly cooled to the lower temperature to prevent the condensing heat exchanger from overheating or operating inefficiently. The cooling fluid may then be routed to the fuel cell at an undesired temperature, or may need to be heated before it is routed to the fuel cell, each of which is an inefficient use of cooling fluid resources. This solution is doubly ineffective because the primary heat exchanger must have a high operational capacity to process all of the cooling fluid. Further, there are significant energy losses caused by processing all of the system fluid through the primary heat exchanger because all of the fluid does not need to be cooled to the lowest set point temperature. These energy losses are not recoverable.
Another solution to the above problem is to provide a secondary heat exchanger. Using the above mentioned example of a fuel cell having a set point temperature higher than the set point temperature of a condensing heat exchanger, the primary heat exchanger could be configured to provide cooling fluid to the fuel cell at the higher temperature. The cooling fluid could then be further cooled by the secondary heat exchanger before it is routed to the condensing heat exchanger. However, the added costs of a secondary heat exchanger make this option undesirable.
Another solution to the above problem has been to use a customized heat exchanger. Using a customized heat exchanger greatly increases the initial assembly cost and the long-term maintenance cost. Customized heat exchangers are much more expensive than standard, so-called “off-the-shelf” heat exchangers, require more maintenance and in the event of component failure, and are extremely difficult to replace.
Another solution is to merely provide independent supply lines or cooling loops. However, the added expense, spatial and weight requirements, and increased complexity make this option undesirable.
Accordingly, there is a need in the industry for an efficient, streamlined, and cost effective cooling system that can adequately control two or more temperatures.